1. Field of the Invention
The invention relates to an antenna coupler for testing a transmitter and/or a receiver device, in particular, a mobile telephone.
2. Related Technology
An antenna coupler is used for testing a transmitter and/or a receiver device, in particular, a mobile telephone. The antenna coupler allows a complete final testing of the mobile telephone, because radio properties of the mobile telephone, in particular the antenna efficiency, are tested. Moreover, in testing the mobile telephone, a plurality of properties and/or parameters of the mobile telephone are investigated, which can be roughly subdivided into transmitter tests and receiver tests. For example, in the case of a transmitter test, a measurement of the phase error, the frequency error, the power and/or the spectrum is implemented. In the case of a reception test, for example, bit-error rates are measured.
The coupling of the transmitter and/or the receiver device is effected via an antenna element provided on the antenna coupler, wherein the coupling factor, which indicates the ratio of the received power relative to the overall transmitted power of the transmitter and/or receiver device, should remain as unchanged as possible in the event of changes of position of the transmitter and/or receiver device. An antenna coupler of this kind is known from DE 101 29 408 A1.
However, the antenna coupler disclosed in DE 101 29 408 A1 has proved inadequate for testing a transmitter and/or receiver device with an antenna arrangement, which provides several antennas, operating in a MIMO (multiple-in multiple-out) system, in a Smart-Antenna system or according to an Antenna-Diversity method.